As a form of art or entertainment

Music is composed and performed for many purposes, ranging from aesthetic pleasure, religious or ceremonial purposes, or as an entertainment product for the marketplace. When music was only available through sheet music scores, such as during the Classical and Romantic eras, music lovers would buy the sheet music of their favourite pieces and songs so that they could perform them at home on the piano. With the advent of the phonograph, records of popular songs, rather than sheet music became the dominant way that music lovers would enjoy their favourite songs. With the advent of home tape recorders in the 1980s and digital music in the 1990s, music lovers could make tapes or playlists of their favourite songs and take them with them on a portable cassette player or MP3 player. Some music lovers create mix tapes of their favourite songs, which serve as a "self-portrait, a gesture of friendship, prescription for an ideal party... and an environment consisting solely of what is most ardently loved."

Amateur musicians can compose or perform music for their own pleasure, and derive their income elsewhere. Professional musicians are employed by a range of institutions and organisations, including armed forces (in marching bands, concert bands and popular music groups), churches and synagogues, symphony orchestras, broadcasting or film production companies, and music schools. Professional musicians sometimes work as freelancers or session musicians, seeking contracts and engagements in a variety of settings. There are often many links between amateur and professional musicians. Beginning amateur musicians take lessons with professional musicians. In community settings, advanced amateur musicians perform with professional musicians in a variety of ensembles such as community concert bands and community orchestras.

A distinction is often made between music performed for a live audience and music that is performed in a studio so that it can be recorded and distributed through the music retail system or the broadcasting system. However, there are also many cases where a live performance in front of an audience is also recorded and distributed. Live concert recordings are popular in both classical music and in popular music forms such as rock, where illegally taped live concerts are prized by music lovers. In the jam band scene, live, improvised jam sessions are preferred to studio recordings.

Composition

"Composition" is the act or practice of creating a song, an instrumental music piece, a work with both singing and instruments, or another type of music. In many cultures, including Western classical music, the act of composing also includes the creation of music notation, such as a sheet music "score", which is then performed by the composer or by other singers or musicians. In popular music and traditional music, the act of composing, which is typically called songwriting, may involve the creation of a basic outline of the song, called the lead sheet, which sets out the melody, lyrics and chord progression. In classical music, the composer typically orchestrates his or her own compositions, but in musical theatre and in pop music, songwriters may hire an arranger to do the orchestration. In some cases, a songwriter may not use notation at all, and instead compose the song in her mind and then play or record it from memory. In jazz and popular music, notable recordings by influential performers are given the weight that written scores play in classical music.

Even when music is notated relatively precisely, as in classical music, there are many decisions that a performer has to make, because notation does not specify all of the elements of music precisely. The process of deciding how to perform music that has been previously composed and notated is termed "interpretation". Different performers' interpretations of the same work of music can vary widely, in terms of the tempos that are chosen and the playing or singing style or phrasing of the melodies. Composers and songwriters who present their own music are interpreting their songs, just as much as those who perform the music of others. The standard body of choices and techniques present at a given time and a given place is referred to as performance practice, whereas interpretation is generally used to mean the individual choices of a performer.citation needed

Although a musical composition often uses musical notation and has a single author, this is not always the case. A work of music can have multiple composers, which often occurs in popular music when a band collaborates to write a song, or in musical theatre, when one person writes the melodies, a second person writes the lyrics, and a third person orchestrates the songs. In some styles of music, such as the blues, a composer/songwriter may create, perform and record new songs or pieces without ever writing them down in music notation. A piece of music can also be composed with words, images, or computer programs that explain or notate how the singer or musician should create musical sounds. Examples range from avant-garde music that uses graphic notation, to text compositions such as Aus den sieben Tagen, to computer programs that select sounds for musical pieces. Music that makes heavy use of randomness and chance is called aleatoric music, and is associated with contemporary composers active in the 20th century, such as John Cage, Morton Feldman, and Witold Lutosławski. A more commonly known example of chance-based music is the sound of wind chimes jingling in a breeze.

The study of composition has traditionally been dominated by examination of methods and practice of Western classical music, but the definition of composition is broad enough to include the creation of popular music and traditional music songs and instrumental pieces as well as spontaneously improvised works like those of free jazz performers and African percussionists such as Ewe drummers.

Notation

In the 2000s, music notation typically means the written expression of music notes and rhythms on paper using symbols. When music is written down, the pitches and rhythm of the music, such as the notes of a melody, are notated. Music notation also often provides instructions on how to perform the music. For example, the sheet music for a song may state that the song is a "slow blues" or a "fast swing", which indicates the tempo and the genre. To read music notation, a person must have an understanding of music theory, harmony and the performance practice associated with a particular song or piece's genre.

Written notation varies with style and period of music. In the 2000s, notated music is produced as sheet music or, for individuals with computer scorewriter programs, as an image on a computer screen. In ancient times, music notation was put onto stone or clay tablets. To perform music from notation, a singer or instrumentalist requires an understanding of the rhythmic and pitch elements embodied in the symbols and the performance practice that is associated with a piece of music or a genre. In genres requiring musical improvisation, the performer often plays from music where only the chord changes and form of the song are written, requiring the performer to have a great understanding of the music's structure, harmony and the styles of a particular genre (e.g., jazz or country music).

In Western art music, the most common types of written notation are scores, which include all the music parts of an ensemble piece, and parts, which are the music notation for the individual performers or singers. In popular music, jazz, and blues, the standard musical notation is the lead sheet, which notates the melody, chords, lyrics (if it is a vocal piece), and structure of the music. Fake books are also used in jazz; they may consist of lead sheets or simply chord charts, which permit rhythm section members to improvise an accompaniment part to jazz songs. Scores and parts are also used in popular music and jazz, particularly in large ensembles such as jazz "big bands." In popular music, guitarists and electric bass players often read music notated in tablature (often abbreviated as "tab"), which indicates the location of the notes to be played on the instrument using a diagram of the guitar or bass fingerboard. Tablature was also used in the Baroque era to notate music for the lute, a stringed, fretted instrument.

Improvisation

Musical improvisation is the creation of spontaneous music, often within (or based on) a pre-existing harmonic framework or chord progression. Improvisers use the notes of the chord, various scales that are associated with each chord, and chromatic ornaments and passing tones which may be neither chord tones not from the typical scales associated with a chord. Musical improvisation can be done with or without preparation. Improvisation is a major part of some types of music, such as blues, jazz, and jazz fusion, in which instrumental performers improvise solos, melody lines and accompaniment parts.

In the Western art music tradition, improvisation was an important skill during the Baroque era and during the Classical era. In the Baroque era, performers improvised ornaments, and basso continuo keyboard players improvised chord voicings based on figured bass notation. As well, the top soloists were expected to be able to improvise pieces such as preludes. In the Classical era, solo performers and singers improvised virtuoso cadenzas during concerts.

However, in the 20th and early 21st century, as "common practice" Western art music performance became institutionalized in symphony orchestras, opera houses and ballets, improvisation has played a smaller role, as more and more music was notated in scores and parts for musicians to play. At the same time, some 20th and 21st century art music composers have increasingly included improvisation in their creative work. In Indian classical music, improvisation is a core component and an essential criterion of performances.

Theory

Music theory encompasses the nature and mechanics of music. It often involves identifying patterns that govern composers' techniques and examining the language and notation of music. In a grand sense, music theory distills and analyzes the parameters or elements of music – rhythm, harmony (harmonic function), melody, structure, form, and texture. Broadly, music theory may include any statement, belief, or conception of or about music. People who study these properties are known as music theorists, and they typically work as professors in colleges, universities, and music conservatories. Some have applied acoustics, human physiology, and psychology to the explanation of how and why music is perceived. Music theorists publish their research in music theory journals and university press books.